Help
End Section Review
End Exam
Answer Edit Confirmation
课程
活动
资料
反馈
题目内容
The concert hall's suspended ceiling is two-inch-thick plaster that reflects low-frequency sound energy; similarly, all wall surfaces are angled and shaped to sound from the stage throughout the audience area.
学员13yqpy
学员19dakm
学员14wgkz
学员15pluv
学员17abhe